(a) Field of the Invention
This invention relates generally to an improved mud motor used in directional drilling of oil and gas wells and more particularly, but not by way of limitation, to an improved flexible, dual, constant velocity or CV, ball joint assembly used with an drive shaft for increased wear life of a mud motor.
(b) Discussion of Prior Art
In directional oil and gas drilling down-hole, a drill pipe string includes a mud motor with a fluid drive rotor inside a stator. The rotor and stator are disposed inside the mud motor's housing and is driven by high pressure fluid. The rotor provides high torque and eccentric, rotation motion for driving the mud motor. The mud motor is used for rotating a drill bit at the end of the drill pipe string. Also inside the mud motor housing is a drive shaft. The drive shaft is used for compensating for eccentric lateral movement from the fluid drive rotor as well as a bend in a mud motor housing of up to 3 degrees. Opposite ends of the drive shaft include universal ball joints with ball bearings for making the lateral movement. The subject invention is a substantial improvement of a flexible universal joint at opposite ends of the drive shaft in the mud motor housing to greatly reduce wear under high torque and compression loading.
In U.S. Pat. Nos. 4,772,246 to Wenzel and 5,704,838 to Teale, universal joint assemblies are disclosed and used with a down-hole mud motor. The prior art patent references don't disclose the unique features and function of the subject high torque, dual, constant velocity, ball joint assembly with multiple rings of ball bearings used with a drive shaft inside a down-hole mud motor housing.